a. A sample of CaCO3 decomposes when heated to form calcium oxide and carbon dioxide. 1.5432 g of CO2 are released in the reaction. Find g of CaCO3 in the original sample. CaCO3 --> CO2 + CaO 1.5432 g CO2*(1 mol of CO2/44.01 g) = 0.035065 mol of CO2*(1 mol CaCO3/1 mol CO2) = 0.035065 mol CaCO3 0.035065 mol CaCO3*(100.09 g/ 1mol CaCO3) = 3.5097 g CaCO3?? b. The original sample was a mixture from which only CaCO3 released carbon dioxide. Calculate the percentage by mass of CaCO3 if original's sample mass was 5.768 g. Do I divide 3.5097 g CaCO3/5.768 g * 100 or must I subtract the grams of CO2 from the original sample's mass? Thanks.